Response Reliability and the Study of Adolescent Substance Use Progression

Article excerpt

Studies of adolescent substance use progression typically infer a sequence of initiation from self reported ages at first use of alcohol, tobacco, marijuana, and hard drugs. This paper examines the reliability of this procedure for a sample of 892 New Jersey youths interviewed on two occasions separated by three years. Individual responses on the second occasion differed substantially from those provided on the first. However, the inferred sequences were consistent as long as 1) first use of alcohol and/or tobacco was considered a single stage, and 2) cases in which individuals initiated the use of two substances in the same year were considered as ambiguous regarding order. The sequences reported were also consistent with the gateway theory that suggests alcohol/tobacco precedes any possible use of marijuana and hard drugs.

INTRODUCTION

An extensive literature review has examined substance use progression, the sequence of substances an individual initiates, and its correlates. Most of this literature has explored substance use progression in the mainstream community (Andrews et al. 1991; Blaze-Temple and Lo 1992; Brook et al. 1982; Donovan and Jessor 1983; Elliott et al. 1989; Fleming et al. 1989; Hays and Ellickson 1991; Kandel 1978; Kandel et al. 1992; Welte and Barnes 1985). These studies consistently suggest that mainstream youths typically followed a pathway starting with the use of alcohol and/or tobacco in early adolescence, possibly followed by use of marijuana and then hard drugs, a sequence referred to as the gateway theory. Individuals who used substances at one stage did not always progress to use of substances at the next. However, individuals who did not use substances at one stage rarely initiated the use of substances associated with later stages.

Several recent studies of explicitly non-mainstream samples drawn from inner-city New York found that many individuals who had become hard drug users started their progression with marijuana instead of the more usual alcohol or tobacco (Golub and Johnson 1994; Mackesy-Amiti, Fendrich and Goldstein 1997). These findings are consistent with detailed psychological and anthropological analyses that suggest the substances an individual uses, frequency, and reasons for use are often strongly influenced by the prevailing substance use culture and an individual's place within it (Schulenberg, Maggs, and Hurrelmann 1997). These cultures can vary across locations and over time. Additionally, several substance use subcultures may simultaneously prevail in a single location at the same time.

Most of the studies referenced above reconstructed individual substance use sequences from their ages at first use for various substances as self reported retrospectively. These measures are prone to a variety of recall and reporting errors that could potentially affect the validity of inferences about the sequences followed. This study examines the reliability (an important component of validity) of age at first use data by comparing self reports provided by a group of youths on two separate occasions. An individual who was telling the truth on both occasions would have provided the same answer at each. However, there are a variety of possible scenarios in which an individual would have provided reliable but incorrect information. Some youths might have constructed stable though inaccurate memories of the events involved. Others might have simply remembered the inaccurate response provided at the first interview. In this sense, reliability is a necessary but not a sufficient indicator of a valid response.

In a summary of the literature, Eisenhower, Mathiowetz and Morganstein ( 1991 ) report that the accuracy of survey responses can be adversely affected by a variety of psychological and communication factors. One possibility is that the clarity with which individuals remember their first use of a substance and their age at the time may simply fade as the years pass. …